The modern communications era has brought about a tremendous expansion of communication networks. Communication service providers and device manufacturers are continually challenged to deliver value and convenience to consumers by, for example, providing compelling network services, applications, and contents. The development of communication technologies has contributed to an insatiable desire for new functionality. Through a communication system such as Mobile Ad Hoc Network (MANET), a social group could be instantly formed by not only people socially connected, but also strangers physically in proximity for conducting instant social activities. This kind of Pervasive Social Networking (PSN) is an essential complement to the Internet on-line social networking and can be very valuable for mobile users, especially when the Internet or cellular networks are temporarily unavailable or costly to access. Trust plays an important role in PSN for reciprocal activities among nearby strangers. It helps people to overcome perceptions of uncertainty and risk and engage in “trust-related behaviors”. During the instant social activities, users are not necessarily acquaintances but more likely strangers. Therefore the users need to balance between benefits received in such reciprocal activities and risks related to communicating with strangers. In this context, it is desirable to authenticate communication parties without knowing their real identities, and at the same time ensure the trustworthiness of authentication in an anonymous way in order to achieve both privacy and security protection.